This invention relates to signal sequencing control means.
Although the following description refers almost exclusively to the use of signal sequencing control means for a smart card, it will be appreciated by persons skilled in that art that the present invention can be used for the control of any signal sequence which needs to be reversed between switching signals on and switching signals off.
Smart card is the common name given to a card, typically of credit card dimensions, containing a microchip and which is used in a variety of applications including securing internet transactions, credit card use, enabling financial transactions, application of ticketing and reward schemes, set top boxes to allow customers to receive and decrypt broadcast signals, for pay-to view channels and/or the like. Smart cards are deemed to be enabled when read in a correct manner by a smart card reader and this requires the sequence of control signals to be enabled in a first order on xe2x80x98power-upxe2x80x99 of the smart card. When use is completed, the sequence of control signals needs to be disabled in a reverse order on xe2x80x98power-downxe2x80x99 of the smart card.
Conventionally the forward and reverse sequences of a smart card are provided by a standard integrated electronic circuit in which includes digital timing means to allow the signals in a particular direction to be activated/deactivated at spaced time intervals. In addition, the electronic circuit is provided with two separate paths to drive the power up and power down signals respectively.
Since smart cards and other electronic devices are becoming increasingly used for both business, leisure and personal pursuits, there is a requirement to make the technology as inexpensive as possible.
An aim of the present invention is to provide a signal sequencing control means which provides an inexpensive and simple solution to activation and deactivation of a sequence of signals.
According to a first aspect of the present invention there is provided a signal sequencing control means for an electronic device, said sequencing control means including an electronic circuit and timing means, to allow a sequence of control signals to be activated in a pre-determined order for operation of the device and deactivated in a reverse order for disabling the device characterised in that the electronic circuit is driven to generate the sequence of control signals in a forward and reverse direction along the same circuit path.
Preferably each control signal is controlled by a resistor/capacitor combination and the signals are controlled by a network of said resistor/capacitor combinations to allow the signals to be activated/deactivated in sequence at pre-determined time intervals.
Preferably the number of resistor/capacitor combinations corresponds to the number of signals to be activated/deactivated in the sequence.
Preferably the resistors of the network are provided in series.
Preferably the sequence of control signals are operated via a number of logic gates.
Further preferably the logic gates are Schmidt Logic Gates.
In one embodiment a logic gate drives voltage through the resistors in a first direction via a diode at the start of the resistor path. A reverse diode is typically provided at the end of the resistor path to drive voltage through the resistors in the reverse direction.
In one embodiment the sequence of the signals in a forwards direction may be different to the sequence of signals in the reverse direction, yet still be driven using the same circuit path.
In one embodiment the electronic device is a smart card and the sequencing control means is provided on/in a smart card reader. The smart card reader typically contains four lines leading to the smart card which need to be enabled in a correct sequence for the smart card to operate. The four lines allow the supply of voltage to the card, place the bi-directional data line of the card in receive mode, apply the clock, and finally enable the reset signal.
According to a second aspect of the present invention there is provided a signal sequencing control means for a smart card interface, said interface including an electronic circuit and timing means to allow a sequence of control signals to be activated in a pre-determined order for operation of the card and deactivated in a reverse order for disabling the card and characterised in that the electronic circuit is driven to generate the sequence of control signals in a forwards and reverse direction along the same circuit path.
According to a further aspect of the present invention there is provided a smart card reading apparatus, said apparatus for reading/receiving and processing signals for a smart card, said reading apparatus having an electronic circuit and wherein the reading apparatus includes timing means to allow a sequence of control signals to be activated in a pre-determined order for operation of the smart card and deactivated in a reverse order for disabling the smart card and characterised in that the electronic circuit is driven to generate the sequence of control signals in a forwards and reverse direction along the same circuit path.
Preferably the smart card reader is built into a broadcast data receiver. The broadcast data receiver typically forms part of a television system and receives and processes data in the form of video, audio and/or auxiliary data broadcast from a remote location by cable, satellite or terrestrial means.
An advantage of the present invention is that the signal sequencing control means uses a single circuit to drive the sequence of signals in the smart card in both a forwards and reverse direction Thus fewer components are required for the signal sequence and the electronic circuitry is therefore inexpensive. This is in contrast to conventional signal sequence control means in reading apparatus in which two separate paths and, as a result different sets of components, are required to drive a sequence of signals in a forward and reverse direction respectively. Conventional circuitry is more expensive than the present invention as more components are required.